Relación del clima social familiar con el rendimiento escolar

Scenario A and Scenario B were training scenarios to familiarise the participant with the interface. The Scenarios A and B-related questions were therefore not considered for a direct comparison between the HMD and computer display proto- type. Only the questions afterScenario C were considered for a direct comparison. However, the scenario-unrelated questions captured the aggregated experiences of the participants over all scenarios.

8.2.1 Scenario-related questions

A clustered Box-and-Whisker plot depicted in Figure 8.4 shows the results from Scenario C-related questions, in which the participant operated either the HMD prototype or computer display prototype.

Figure 8.4. Clustered Box-and-Whisker plot with Median and IQR fromScenario C-related7-point Likert scale questions.

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The vertical axis indicates the agreement (1 = Completely Disagree and 7 = Completely Agree) with the statements 1-4. The labels with statement numbers on the horizontal axis refer to the following statements:

1. It was easy to identify the reason why the SAV had stopped;

2. I had a very good understanding of the traffic and situation around the vehicle; 3. I felt strongly connected to the vehicle in the scenario;

4. I would feel really confident operating the vehicle.

The Fisher’s exact test on the medians of the results from Statements 1 to 4 indicate, with a 95% confidence, that the central tendencies between using an HMD and computer display prototype are similar. The results show that participants were in agreement that it was equally easy to identify the reason why the vehicle stopped using both interfaces. Also, from the results, it can be observed that an HMD and computer display provide a similar understanding of the traffic and situation around the vehicle. A small variance is observed inStatement 1 and 2 for respectively both interfaces. A larger variance can be observed for the computer display prototype in Statement 3 and 4 (with IQR=2.25 resp. IQR=3.25). These findings indicate that a stronger disagreement can be observed, whether participants felt strongly connected to the SAV and would feel confident operating the vehicle while using a computer display. In comparison, results from Statement 3 and 4 when using the HMD prototype show stronger agreement (resp. IQR=1.25, IQR=1.25); the answers are clustered around the median.

8.2.2 Scenario-unrelated questions

The Box-and-Whisker plot inFigure 8.5 depicts the results from the six scenario- unrelated questions, after having completed all four scenarios. The vertical axis indicates the agreement (1 = Completely Disagree and 7 = Completely Agree). The labels on the horizontal axis refer to the following statements:

I I prefer to use the computer display prototype instead of the HMD prototype; II The HMD prototype made it easier for me to interpret the traffic situation; III The HMD prototype provided me with more information about the traffic

situation;

IV The HMD prototype gives me more visibility around the vehicle;

V Using the HMD prototype makes it easier to predict how the traffic situation will develop;

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Figure 8.5. Box-and-Whisker plot with Median and IQR fromScenario-unrelated

7-point Likert scale questions.

Results from Statement I (MED=3, IQR=2.5) indicate that the participants did not have a distinct preference for using either the HMD or computer display prototype. However, the results fromStatements II and IV are not in line with this finding; they show that an HMD was more beneficial than the computer display regarding interpretation of the traffic situation and visibility. More specifically, in Statement II, the participants agreed that the HMD prototype made it easier to interpret the traffic situation (MED=6, IQR=1.5). Similarly, in Statement IV, the participants stated that the HMD gave them more visibility around the SAV (MED=6, IQR=2). Findings fromStatement III are indecisive, results do not show that the participant’s answer are strongly clustered (MED=5, IQR=3.5). Hence, it cannot be concluded that the HMD prototype or computer display provided them with more information about the traffic situation. Results from Statement V indicate that the participants found that using the HMD prototype does not make it significantly easier to predict how a traffic situation will develop (MED=5, IQR=2.25). All of the participants expressed agreement with the statement that future control rooms should use an HMD prototype (MED=5.5, IQR=2).

A comparison between the experts and non-experts for all scenario-unrelated statements is shown in Table 8.1. The experts are in a stronger agreement with Statements II, V and VI than the non-experts. That is, the experts agreed more strongly than the non-experts that the HMD made it easier for them to both interpret (Statement II, MED=6) and predict the traffic situation (Statement V, MED=6) than the computer display. Also, the experts were more decisive that the future control rooms should use an HMD rather than a computer display (Statement VI, MED=6.5). With regard to the scenario C-related questions, no significant dif-

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ferences between expert and non-expert participants were observed. Experts Non-experts Statement I 2.5 4 Statement II 6 5.5 Statement III 4 5 Statement IV 5.5 6 Statement V 6 4.5 Statement VI 6.5 5

Table 8.1. A comparison of the median results between experts and non-experts based onscenario-unrelatedquestions.

8.2.3 Thematic analysis

Based on the objectives outlined at the start of the evaluation a categorisation is made between findings about confidence and awareness, implicit performance and the user experience of using an HMD. Thematic analysis of the transcribed audio recordings revealed a number of topics with regard to confidence and awareness.

• Three participants stated that when using the HMD prototype they were more looking around and taking in what is happening. When using a computer display, the participants found themselves looking more at the interface in comparison with the HMD prototype.

• Four participants expressed that when using an HMD they feel and understand better what is going on. For five participants it felt more ’natural/intuitive’ to use an HMD. A majority, seven participants, stated that by using the HMD they felt like they were more in the situation and ’with the vehicle’.

• Two participants indicated they would feel weird if they would have to take control using a computer display because they experienced to be distant from the vehicle. Moreover, two participants also expressed that they would feel more confident and safe to operate a vehicle when using the HMD because the computer display did not give a satisfactory overview and awareness of surroundings. One participant mentioned“If I were to command the vehicle, I would use the Head-Mounted Display because it would enable me to look aside more quickly”.

• Four participants mentioned that the HMD would not be necessary for all situations. For example, the computer display would work better in situations when the operator wants to get a quick overview of the situation. However, the HMD would be preferable in more complex situations where traffic is quickly changing or the operator needs to watch and drive the SAV.

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The following aspects detail key user experiences when using the HMD prototype: • Two participants found the first use of the HMD overwhelming. Also two

participants mentioned that they were uncomfortable at first when using the HMD. Three participants felt more ’shaky/dizzy’ while using the HMD in contrast to using the computer display.

• Also, three Participants indicated they are able to easily look around by turn- ing their head when using an HMD.

• For driving tasks, three participants mentioned that they would like to have a simple and straightforward big button to continue automated operations. Alternatively, three other participants mentioned that they would like to steer the SAV by drawing a path on the ground ahead of the SAV.

Qualitative evidence of significant variances in performance between the HMD and computer display could not be found. No differences were recorded between the HMD and computer display concerning the number of times participants were able to observe the appearing warning message upon the moment the vehicle came to a stop.